Textron Aviation Safety Initiative January 21, 2017 Company Private Company Private
Cessna 172 Skyhawk Beech Bonanza Cessna 208 Caravan Beechcraft 1900D Textron Aviation is the company formed from Cessna and Beechcraft in March 2014 together 250,000+ airplanes have been delivered Cessna O-2 Skymaster Beechcraft T-6A Texan II Cessna Latitude Hawker 4000
Textron Aviation Piston Engine Airplanes 205,000+ produced since 1946 Of which 190,000 produced before 1987 Average age is 43 years old Certified CAR 3 Made of Aluminum Single Engine Airplanes flown 100-150 hours annually
Textron Aviation Piston Engine Airplanes Over sixty-five percent of active piston engine airplanes are Cessna or Beechcraft 2015 Piston Engine Usage - Active US Aircraft Total of 141,141 Airplanes Representing All Manufacturers
Textron Aviation Safety Initiative Between 2000-2011 Cessna Aircraft developed new structural inspection programs to assure the continued safe operation of piston engine airplanes For single engine airplanes, visual inspection techniques are utilized to detect Corrosion Cracks caused by metal fatigue New structural inspection programs for Beechcraft airplanes are in work
Textron Aviation Safety Initiative Why Inspect? Corrosion (rust) and metal fatigue are inevitable Corrosion and metal fatigue reduce the load carrying capability of the airframe Like people, airplanes age, and more frequent and intrusive inspections are required to maintain health (safety)
Textron Aviation Safety Initiative Cessna SID Implementation in New Zealand Mandatory compliance 90 to 95% of inspected airplanes required maintenance action 20% of those which required action needed major repair 80% of the findings were corrosion and 20% cracking Most common cracking area is around front and rear door posts Another common area of cracking is at lower strut fuselage attachments
Corrosion Prevention The key to corrosion prevention is to keep the airframe free of moisture A major contributing factor to corrosion is the environment Aircraft that operate in coastal environments are more susceptible to metal corrosion While water vapor already has a corrosive effect, the water vapor and salt combination found in coastal environments creates a powerful corrosive agent Aircraft that operate in areas that contain high amounts of industrial particles and fumes in the atmosphere also are more susceptible to corrosion Aircraft that operate in areas where environmentally friendly runway deicers are used (i.e., potassium formate, potassium acetate, etc.) are more susceptible to corrosion
Corrosion Severity Map
Corrosion Prevention There are several common options available to shield the aluminum from electrolytes including: Cladding 2024 sheet can be coated ("clad") with very thin layers (.001 ) of pure aluminum to protect from corrosion, known as 2024-T3 AlClad The sheet material is vulnerable when the cladding is compromised at edges, drilled rivet holes, or if it is scratched Most airframe corrosion occurs at seams and joints, which is why cladding alone is not sufficient Additional steps are necessary to protect seams, holes, and un-clad parts from exposure to electrolytes
Corrosion Prevention There are several common options available to shield the aluminum from electrolytes including: Chemical Treatments Alodine or other chemical treatments are used to enhance the corrosion resistance of the pure aluminum cladding
Corrosion Prevention There are several common options available to shield the aluminum from electrolytes including: Sealants Paint is the most commonly used sealant for corrosion protection and is the best defense against airframe corrosion Modern polyurethane aircraft paints create a thick, impenetrable barrier that effectively keeps moisture away from the metal, and lasts a long time - - 10 years or more Paint only protects the exterior of the airframe Cessna airframe interiors of most pre-1986 airframes were not painted (primed) Many Beech airframe interiors were only partially painted (primed)
Corrosion Prevention There are several common options available to shield the aluminum from electrolytes including: Corrosion Preventative Compounds (CPCs) Effective means for protecting those parts of an airframe that were not originally protected from corrosion Guidelines for application and use of CPCs are provided in the revised Service Manual CPCs must be reapplied periodically The following CPCs are recommended for use on Textron Aviation airplanes Dry film compounds: Non-dry grease: ARDROX AV-8* and AV-15 Cor-Ban 23* and Cor-Ban 35 Cor-Ban 27L Non-dry oil: Corrosion X * Preferred where high penetration of corrosion inhibiting compound is required.
Corrosion Results Corrosion is responsible for approximately: 7% of the airworthiness directives 1 20% of service difficulty reports (SDRs) Corrosion can be deadly Corrosion contributed to 91 accidents/incidents in the United States between 1983 and 1994 2 These and other accidents have resulted in hundreds of fatalities 3 As airplanes continue to age, these numbers are likely to increase 1 Swift, S., Rusty Diamond, 24 th ICAF Symposium, May 2007. 2 Hoeppner D,, Chandrasekaran V., Taylor A., Review of Pitting Corrosion Fatigue Models, 20 th ICAF Symposium, 1999. 3 Aviation Safety Network Database, http://aviation-safety.net/index.php
Corrosion and Metal Fatigue Corrosion and metal fatigue both reduce the load carrying capability of the airframe Corrosion and fatigue are not entirely independent processes - corrosion affects the expected fatigue life of airframe parts Corrosion pitting creates a stress concentration which leads to crack initiation and potentially faster crack Corrosion reduces the thickness of a part and therefore increases the stress in the part View of Spar Cap Fracture Surface View of Spar Cap Lower Surface
Corrosion Examples Beech 18 Wing Front Spar Beech Bonanza/Baron Control Surfaces Beech Bonanza/Baron Front Spar Leading Edge Lower Hinge-Pin Attachment Cessna 177 Wing Spar Cessna 200 Series Wing Spar Cessna 182 Lower Strut Fitting Cessna Single Engine Wing Spar Cessna Single Engine Rudder Pedal Cessna Single Engine Main Landing Gear
Beech Bonanza/Baron Control Surfaces
Beech Bonanza/Baron Front Spar Leading Edge Lower Hinge-Pin Attachment Special Airworthiness Information Bulletin (SAIB) CE-15-22
Cessna 177 Wing Spar 177B Found as a result of SEB-57-03 Special Airworthiness Information Bulletin (SAIB) CE-16-16 177RG
Cessna 200 Series Wing Spar Found as a result of SID Inspection 57-11-01
Cessna 182 Lower Strut Fitting Found as a result of SID Inspection SID 57-40-01
Wing Spar Corrosion Found as a result of CPCP Inspection
Cessna Single Engine Rudder Pedal Fractured Pedal Arm Tube SID 27-20-01
Cessna Single Engine Main Landing Gear Made from 6150M High- Strength Steel A pit as small as.005 can initiate a fatigue crack which will result in fracture of the gear Keep surface painted with polyurethane paint and blend out pits per Service Manual Rust Model 182 Flat Spring Gear SID 32-13-01
Cessna Single Engine Main Landing Gear.017 Pit
Metal Fatigue Aviation has had to address metal fatigue in the design and inspection of airframes since 1954 Fatigue can be deadly Metal fatigue contributed to 2240 deaths in 1885 airplane accidents between 1927 and 1980 1 The five most common fatigue crack initiation sources in these accidents were: (1) bolt, stud or screw; (2) fastener or other hole, (3) fillet, radius or sharp notch; (4) welds and (5) corrosion Over 700 people have died in fatigue related accidents since 1980 2 1 Campbell and Lahey 1984, A Survey of Serious Aircraft Accidents Involving Fatigue Fracture, International Journal of Fatigue, January 1984 2 Investigation into Ansett Australia Maintenance Safety Deficiencies and the Control of Continuing Airworthiness of Class A Aircraft, Appendix 8 from the Australian Transport Safety Bureau s web site, www.atsb.gov.au.
What is Metal Fatigue? Fatigue Under Microscope Typical Fatigue Failure
FAA Regulations Through the Years High-Profile Accidents Comet 1954 F111 1969 Dan Air 1977 Aloha Airlines 1988 Beech T-34 1999-2004 1940 1950 1960 1970 1980 1990 2000 CAR FAA Textron Aviation CAR/FAA Part 23 Regs & Policies Beech 35 Certified 1947 Beech 23 Certified 1962 Cessna 172 Certified 1955 Cessna 206 Certified 1963 Wing Fatigue Evaluation 1969 Instructions for Continued Airworthiness 1980 Fuselage Fatigue Evaluation 1965 Empennage Fatigue Evaluation 1989 AC91-82 Fatigue Management Program 2008
Key Lessons Learned From High Profile Accidents Comet Fatigue must be considered in design, not just static strength 2,703 & 3,680 total hours F111 - Manufacturing or accidental damage must be considered 105 total hours
Key Lessons Learned From High Profile Accidents Boeing 707-321C - Fail-safe alone doesn t work, need inspections 47,621 total hours
Key Lessons Learned From High Profile Accidents Boeing 737 - Inspection programs do not keep airplanes safe indefinitely. Eventually there needs to be a terminating action of modification or retirement. 35,496 total hours
Key Lessons Learned From High Profile Accidents Beech T-34 Detailed inspection programs are needed for the entire airframe, not just for known areas of cracking 3200, 8257 & 9316 total hours
Case Study Cessna 402C Model 402C designed in 1979 Twin-Engine unpressurized airplane Seats up to 9 passengers Often used for cargo hauling or scheduled airline passenger service
Case Study Cessna 402C Wing spar cracking discovered in 1999 led to addition of wing spar strap (SID 57-10-16) Engine beam cracking discovered in 2015 led to life limit of engine beams (SID 54-10-01) Nacelle fitting (engine beam to wing attachment) cracking discovered in 2016 led to life limit of nacelle fittings Carry-thru forward spar cracked in 2017 (SID 57-10-14)
Case Study Cessna 210 Model 210 with cantilevered wing designed in 1967 Single-Engine unpressurized high performance airplane Seats up to 6 passengers Used for a variety of missions including cargo hauling, geophysical survey, sight seeing as well as private usage
Case Study Cessna 210 Eight reports of wing spar cracking reported in 2012 (SID 57-11-03) Horizontal stabilizer aft attachment fitting cracking discovered in 2011 Horizontal stabilizer forward spar cracking discovered in 2011 (SID 55-10-01)
Metal Fatigue Examples Beech Bonanza/Baron Rudder Brake Pedal Pivot Hole Beech Bonanza/Baron Flight Control Cables Cessna 180/185 Tailcone Stringer Cessna 172 (Restart) FS 108 Bulkhead Cessna 172/182/206/210 Forward Doorpost at Strut Attachment Cessna 150/152 Vertical Stabilizer Attach Cessna 177 Lower Wing Spar
Beech Bonanza/Baron Rudder Brake Pedal Pivot Hole Fractured Rudder Brake Pedal Pivot Hole
Beech Bonanza/Baron Flight Control Cables Beech V35A Aileron Control Cable CASA AD/GENERAL/87 - primary flight control cable assemblies using terminals constructed of SAE-AISI 303 Se or SAE-AISI 304 stainless steel must be replaced after 15 years
Cessna 180/185 Tailcone Stringer Special Airworthiness Information Bulletin (SAIB) CE-16-16 SID 53-10-01 AD under consideration
Cessna 172 (Restart) FS 108 Bulkhead Found as a result of SID Inspection SID 53-12-03
Cessna 172/182/206/207/210 Forward Doorpost at Strut Attachment AD or SAIB under FAA consideration SID 53-12-01 Crack
Cessna 150/152 Vertical Stabilizer Attach Crack Special Airworthiness Information Bulletin (SAIB) CE-16-03 SID 55-11-02
Cessna 177 Lower Wing Spar Special Airworthiness Information Bulletin (SAIB) CE-16-16 SID 57-11-03
SID Inspections Inspections Based on field history Reviewed by customer focus group Inspection Details Corrosion prevention and control program Directed visual inspection for corrosion ~15-20 visual inspections to look for cracks Boroscope and magnifying glass required to complete inspections SID inspections are designed to be accomplished at an annual when airplane is opened up Anticipated cost is dependent on flight hours and overall airplane condition Approximately 10 hours for low time airplane maintained per service manual Approximately 25 hours for high time airplane maintained per service manual Any required repairs are additional cost
Summary Safety is a partnership between owners (maintainers), manufacturers and the FAA Comply with airworthiness directives Report anomalies Send Pictures!!